Champion is a small, melancholy boy adopted by his grandmother, Madame Souza. Noting the child's passion for cycling, Madame Souza puts him through years of relentless training. The years go by. Champion becomes a top cyclist and makes in into the famous Tour de France.
However, during the race, he is kidnapped by two mysterious men in black. Madame Souza sets off to find him, accompanied by her faithful dog Bruno. Their search takes them across the ocean, to the vast metropolis of Belleville. There they meet the "Triplets of Belleville", three eccentric women who were the music hall stars in the 1930. The trio decided to take Madame Souza and Bruno under their wing. Bruno's nose puts them on the trail of the Champion, but will they succeed in outsmarting the powerful French mafia?